1. Field of the Invention
The present invention relates generally to devices for imprinting fixed and variable information on business forms and similar documents, and is particularly concerned with a platen disabling mechanism to prevent double imprinting. The platen disabling mechanism of the present invention is disarmed only when a credit card is positioned on the imprinter bed and at least one of the variable imprinting indicia on the imprinter has been reset. After the imprinting the disabling mechanism prevents further imprinting until again disarmed.
2. Description of the Prior Art
Variable imprinting devices for transferring to a printed form the fixed and variable information relating to a business transaction are well known and have been in general use in various types of retail establishments for many years. Typically, the purchaser presents the retailer with a plastic credit or charge card, upon which are embossed the customer's name, address, account number, and other pertinent information in raised numerals and letters. The vendor places the card together with a prepared form containing one or more carbon duplicates, onto the imprinting device. Generally, the imprinter also includes an affixed metal plate (sometimes referred to as the "merchant plate"). On this metal plate are embossed the name, address and other pertinent information of the retail establishment in raised numerals and letters, so that this information can also be transferred to the form by imprinting. In addition to the "fixed " type of information, as embossed on cards, in some cases, the date of the transaction as set on printing wheels mounted adjacent to the printing surface is also transferred to the form by the imprinter. The remaining "variable " information, such as the price of the goods or services purchased, the applicable taxes, and so on, is set on the machine before the imprinting operation is carried out, and is transferred by imprinting to the form along with the customer's account information, and the name and location of the vendor establishment. The imprinting of variable information is usually done by means of an adjustable set of printing or digit wheels which are brought into contact with the form during the imprinting operation. A common arrangement for setting the variable information is to install a digit wheel assembly within the imprinter housing so that it protrudes slightly through a slot or cut-out in the print bed. Adjustment of the digit wheel settings is usually accomplished by means of slidable tabulator keys or rotatable thumbwheels.
The imprinting of both the fixed and variable data onto the forms is accomplished by the passage of one or more platens across the surface of the forms with the underlying embossed cards and the set digit wheels. To move the platens over the forms, the platens are mounted on a carriage which is further mounted for slidable movement along the bed of the imprinter on which a form and the embossed cards and digit wheels are positioned. The carriage is moved from a starting position across the surface of a form, and then is moved back to the starting position.
Unrestricted movement of the platen carriage over a form with both an underlying customer credit card and digit wheels however, can result in inadvertent double imprinting, i.e. a first imprinting of the form with fixed and variable data followed by a second imprinting on the same form or on a different form of the same data. The imprinting of the same variable data results from not rotating at least one of the digit wheels prior to the second imprinting. Such double imprinting on a second form can result in an inaccurately imprinted form with the inaccurate charge information being recorded in an accounting system against the credit account of the second card holder. Whereas, the double imprinting of the same form with the same data often results in a uselessly imprinted form, because the double imprinting often causes double images or smudging. Since at least one of the imprinted sheets must be machine-readable, it is important that the imprinting of data on the form be accomplished without smudging. Therefore, a double imprinting of the same data on the same form invariably results in a smudged or double image which renders the form useless.
Another possible cause for error in imprinting forms is the inadvertent failure of the imprinter operator to position the customer's credit card under the form for imprinting. Then the imprinted form fails to include the customer's account information.
Failing to reset variable data between imprintings, or failing to assure mounting of a credit card on the imprinter bed are problems which previously have been individually recognized in the design of imprinters. For example, a variable imprinter with a disabling mechanism armed to prevent double imprinting of the same variable data and disarmed after resetting of at least one of the variable data print wheels is disclosed in co-pending U.S. patent application Ser. no. 560,409, now abandoned entitled "Variable Field Imprinter With Disabling Means", filed by Walter Weickert on Dec. 12, 1983. In this patent application an imprinter is disclosed where the platen carriage on being returned to the starting position for imprinting arms the disabling mechanism and rotation of a variable data print wheel disarms the disabling mechanism.
Another type of imprinter disabling mechanism is disclosed in co-pending U.S. patent application Ser. no. 306,495, now U.S. Pat. No. 4,651,642 entitled "A Credit Card Imprinter With Disabling Means", filed by David E. Gravelle on Sept. 28, 1981, as a continuation application from Ser. No. 91,308 filed on Nov. 5, 1979. In this patent application an imprinter, which may not have variable data imprinting capability, is disclosed where the platen carriage is prevented from being moved from the starting position to make an imprinting if a credit card is either not positioned for imprinting on the imprinter bed or is incorrectly positioned for imprinting.